The invention relates to a semiconductor configuration having a semiconductor body with connection zones, a channel zone and a control electrode surrounded by an insulating layer.
Such semiconductor configurations with first and second connection zones and a channel zone of the same conductivity type are, for example, xe2x80x9cACCUFETsxe2x80x9d (Accumulation-Mode Field-Effect Transistors), as are described in the article xe2x80x9cThe Accumulation-Mode-Field-Effect-Transistor; A new ultralow on-resistance MOSFETxe2x80x9d by B. Jayant Baliga, IEEE ELECTRON DEVICE LETTERS, Vol. 13, No. 8, August 1992.
U.S. Pat. No. 5,844,273 describes such an ACCUFET having an n-doped drain zone as a first connection zone, the drain zone being provided in the region of a rear side of a semiconductor body, an n-doped source zone as a second connection zone, the source zone being provided in the region of a front side of the semiconductioe body, and a weakly n-doped channel zone formed between the source zone and the drain zone. A gate electrode as a control electrode of the ACCUFET extends in the vertical direction of the semiconductor body adjacently to opposite sides of the weakly n-doped channel zone between the source zone and the drain zone. When a voltage is applied between the drain zone and the source zone, a current flows in the vertical direction of the semiconductor body in the channel zone. When a negative drive potential is applied to the gate electrode, a conducting channel in the channel zone between the drain and source zones is pinched off and the ACCUFET turns off. What is crucial for the dielectric strength of such an ACCUFET is, inter alia, the thickness of an insulation layer surrounding the gate electrode. In the ACCUFET in accordance with the above-mentioned U.S. Pat. No. 5,844,273, the drain zone has, beside a heavily n-doped region, a more weakly n-doped region adjoining the channel zone and the gate electrode. The distancexe2x80x94determined by the more weakly doped region of the drain zonexe2x80x94between the channel zone, or the gate electrode, and the more heavily doped region of the drain zone determines, inter alia, the dielectric strength of the device.
As a result, with regard to the dielectric strength, in the known ACCUFET the minimum height thereof in the vertical direction of the semiconductor body is determined by the dimensions of the gate electrode in the vertical direction of the semiconductor body, and if appropriate the dimensions of the more weakly doped region of the drain zone in the vertical direction. In the known ACCUFET, the heavily doped region of the drain zone, which reaches from a rear side of the semiconductor body up to the channel zone, or the more weakly doped region of the drain zone, takes up a considerable space of the semiconductor body. Its dimensions in the vertical direction are thus determined by the dimensions of the semiconductor body in the vertical direction minus the dimensions of the gate electrode and the dimensionsxe2x80x94prescribed by the desired dielectric strengthxe2x80x94in the vertical direction of the more weakly doped region of the drain zone. A significantly smaller xe2x80x9cheightxe2x80x9d of the drain zone, or of the heavily doped region thereof, would suffice in many cases for a reliable functioning of the ACCUFET. In the known components, the drain zone thus takes up a considerable bulk proportion of the available semiconductor body which remains substantially unutilized.
It is accordingly an object of the invention to provide a semiconductor configuration which overcomes the above-mentioned disadvantages of the heretofore-known configurations of this general type and which achieves a higher packing density, that is to say more field-effect-controllable components with first and second connection zones and channel zones of the same conductivity type and control electrodes for driving can be accommodated in the semiconductor body. In this context, xe2x80x9cmore componentsxe2x80x9d also means more identically constructed cells of a component whose respective connection zones and channel zones are jointly interconnected.
With the foregoing and other objects in view there is provided, in accordance with the invention, a semiconductor configuration, including:
a semiconductor body including a first connection zone of a first conductivity type, a second connection zone of the first conductivity type, a channel zone of the first conductivity type, at least one control electrode, and an insulation layer;
the channel zone of the first conductivity type being formed between the first connection zone and the second connection zone;
the insulation layer surrounding the at least one control electrode;
the at least one control electrode extending, adjacent to the channel zone, from the first connection zone to the second connection zone;
the semiconductor body defining a vertical direction and a lateral direction; and
the first connection zone, the second connection zone and the at least one control electrode extending in the vertical direction such that, when a voltage is applied between the first and second connection zones, a current path along the lateral direction is formed in the channel zone.
In other words, the object of the invention is achieved when the first connection zone, the second connection zone and the control electrode extend in the vertical direction of the semiconductor body in such a way that when a voltage is applied between the first and second connection zones, a current path is formed in the lateral direction of the semiconductor body in the channel zone.
The properties of the semiconductor configuration according to the invention, in particular with regard to its dielectric strength, are determined, inter alia, by the thickness of the insulation layer of the control electrode, the length of the channel zone in the lateral direction of the semiconductor body and, if appropriate, the dimensions of a more weakly doped region of the first connection zone between the channel zone and a more heavily doped region of the first connection zone.
The dimensions of the cross section of the channel zone transversely with respect to the current direction influence the conductivity of the component formed in the semiconductor configuration according to the invention. In the configuration according to the invention, the first and second connection zones, the channel zone and the control electrode can extend into the semiconductor body virtually as far as desiredxe2x80x94only limited by the height of the semiconductor bodyxe2x80x94in the vertical direction of the semiconductor body. This makes it possible to enlarge the cross section of the channel zone without influencing the dielectric strength of the component formed in the semiconductor configuration according to the invention, the dielectric strength being influenced by the dimensions of the component in the local direction. A larger part of the semiconductor body can be utilized as channel zone in the semiconductor configuration according to the invention than according to the prior art.
The control electrode is preferably in the form of a plate, its longitudinal extent in a first lateral direction of the semiconductor body and in the vertical direction of the semiconductor body being significantly greater than in a second lateral direction of the semiconductor body transversely with respect to the first lateral direction. The control electrode configured in the form of a plate along the channel zone, or on both sides of the channel zone, requires less space in the semiconductor body and so the packing density that can be achieved is additionally increased, that is to say that the number of field-effect-controllable components that can be realized in a predetermined semiconductor body increases.
Preferably, the first connection zone, the second connection zone, the channel zone and the control electrode extend from a front side of the semiconductor body in the vertical direction thereof approximately up to the rear side thereof in order that the semiconductor body is virtually completely utilized for a controllable component.
A further embodiment provides for a control electrode to be shared in each case by two first connection zones, the control electrode extending from one of the two first connection zones to the other of the two first connection zones adjacently to the second connection zone and the channel zone. This measure additionally contributes to a space gain and increases the number of components, or cells of a component, which can be accommodated in the semiconductor body.
Preferably, contact can be made with the second connection zone from a front side of the semiconductor body, and with the first connection zone from a rear side of the semiconductor body. In an embodiment having a plurality of identically constructed cells, in order to make contact with the first connection zones of the individual cells, a doped layer of the first conductivity type is provided in the region of the rear side of the semiconductor body, the dopant concentration of which layer preferably corresponds to the dopant concentration of the first connection zones, and which layer is connected to the first connection zones extending vertically. A metal layer is preferably applied to this layer provided on the rear side, which metal layer can be connected to a supply potential for the first connection zone.
A further embodiment provides for regions made of a readily electrically conductive material, preferably made of polysilicon or a metal, to be introduced into the vertically extending first connection zones and the vertically extending second connection zones. These readily electrically conductive regions, which are preferably connected to respective supply potentials for the first and second connection zones, have the effect that the respective potential is approximately constant in the vertical direction of the first and second connection zones.
According to another feature of the invention, the first connection zone and the second connection zone define the lateral direction as extending from the first connection zone to the second connection zone; the first and/or second connection zone has a first dimension in the vertical direction and a second dimension in the lateral direction; and the first dimension is smaller than the second dimension.
According to yet another feature of the invention, the lateral direction is a first lateral direction extending from the first connection zone to the second connection zone; the semiconductor body defines a second lateral direction transverse to the first lateral direction; the at least one control electrode is a substantially plate-shaped control electrode having a respective longitudinal extent in the vertical direction and in the first lateral direction and a lateral extent in the second lateral direction; and the respective longitudinal extent is greater than the lateral extent.
According to another feature of the invention, the first connection zone has a first zone with a first dopant concentration and a second zone with a second dopant concentration; the first dopant concentration is higher than the second dopant concentration; and the second zone is formed between the first zone and the channel zone.
According to a further feature of the invention, the first connection zone has a first zone with a first dopant concentration and a second zone with a second dopant concentration; and the second zone completely surrounds the first zone in the lateral direction.
According to another feature of the invention, the first connection zone has a first zone with a first dopant concentration and a second zone with a second dopant concentration; the second connection zone has a third dopant concentration; the channel zone has a fourth dopant concentration; and the fourth dopant concentration is lower than the first and third dopant concentrations.
According to a further feature of the invention, the semiconductor body has a rear side; a layer of the first conductivity type is disposed at the rear side; the first connection zone has a first zone with a first dopant concentration and a second zone with a second dopant concentration; the layer has a fifth dopant concentration; the fifth dopant concentration substantially corresponds to the first dopant concentration; and the layer is connected to the first connection zone.
According to another feature of the invention, a further first connection zone is provided; a further channel zone extends between the further first connection zone and the second connection zone; and the at least one control electrode extends, adjacent to the second connection zone, the channel zone and the further channel zone, from the first connection zone to the further first connection zone.
According to another feature of the invention, the semiconductor body has a front side and a rear side; and the first connection zone extends, in the vertical direction, from the front side to the rear side of the semiconductor body.
According to another feature of the invention, the semiconductor body has a rear side; and an electrically conductive layer is disposed on the rear side of the semiconductor body for making contact with the first connection zone.
According to yet another feature of the invention, an electrically conductive zone is introduced in the first and/or second connection zone for making contact with the first and/or second connection zone.
According to another feature of the invention, the electrically conductive zone is formed of polysilicon or a metal.
According to another feature of the invention, the first dopant concentration is higher than 1018 cmxe2x88x923.
According to a further feature of the invention, the second dopant concentration is about 5xc3x971015 cmxe2x88x923.
According to another feature of the invention, the fourth dopant concentration is less than 1014 cmxe2x88x923.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a field-effect-controllable semiconductor configuration with a channel zone running laterally, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.